1. Field of the Invention
The present inventions relate to apparatus and methods for supporting or holding items, for example clamps, and methods of using clamps to hold payloads on aircraft engines and other equipment.
2. Related Art
Many devices and methods exist for holding or supporting items such as work pieces or payloads. For example, some devices are freestanding, such as cable ties, while others are fixed to or supported by a support surface such as a wall, housing, bracket or other stationary member. The fixed devices are typically single-piece or multiple-piece devices held in place by fasteners such as rivets, nuts and bolts, and the like. In simple arrangements, these fixed devices are relatively simple to assemble, install and maintain, while more complicated arrangements require more time-consuming procedures to install and to service or maintain. For example, cable clamps used in open and uncrowded environments are easy to assemble and maintain, while those used in close quarters may need close attention and dexterity to properly assemble and install the clamp. Clamps having or requiring greater numbers of parts often require more attention to assemble, more time to install and often are more difficult to maintain or service.
In many applications, such as in aerospace applications and including aircraft engines, for example, wiring, cable and tubing are often held in place by a number of clamps. The clamps may take the form of a loop clamp or P clamp, where the clamp is a one-piece structural element (typically with a rubber or elastomeric cushion around the structural element to protect the payload), closed and held in place with fasteners such as a nut and bolt. The use of separate fasteners increases the part count, and therefore the weight and the cost, increases the likelihood that a part will be lost or improperly assembled, and increases the time required for assembly, inspection, maintenance, service and repair as well as replacement. Precise assembly steps and tightening requirements are typically mandated, especially for aircraft applications, leading to time-consuming assembly, inspection, maintenance, and replacement procedures. With more parts and procedural steps, part costs and assembly costs increase, and there is a greater possibility of mistake during installation. More parts also lead to more weight not only for the individual parts but for the equipment as a whole.
Loop clamps or P clamps are not only relatively difficult and costly to assemble and sometimes to manufacture, they also undergo stresses and strains under normal operating conditions caused by vibration or other effects in the engine or other equipment to which the clamps are mounted. For example, because the loop clamp is symmetrical about only one plane, bisecting the structural element and the cushion, relatively large moments, or off-center sideways forces, are produced in the clamp, and therefore the cable or other payload held or supported by the clamp. These moments may result in higher forces or stresses than desired being placed on the payload.
Other clamps used for holding or supporting payloads and work pieces include saddle clamps. Saddle clamps are two piece structural devices, each piece sometimes having a cushion, where the two pieces are held together and held in place typically with a pair of nuts and bolts. Such clamps may be used in aircraft such as in the fuselage and wings, as well as for other applications. As with the loop clamp, the saddle clamp has a number of parts, all of which are removed and set aside when the payload is to be moved or other service is to be performed. The saddle clamp is also limited by its configuration to a relatively small range of payload sizes for a given clamp size. If the size of payload is increased or decreased after the initial installation, a saddle clamp of a different size is often required, which also requires time to properly determine the size, order or obtain the clamp and install it. More flexibility in servicing the equipment would result if the saddle clamps could accommodate more than one or a few sizes of payload without having to change clamps.
The conventional saddle clamps hold or support the payload in a number of different ways, and some designs have gaps where no contact is made between the clamp and the payload, or the payload is not adequately supported. In some designs, where the payload includes wires that are not wrapped in a fully enclosed bundle, wires may wedge between parts of the clamp. Consequently, the payload may not have the support that may be desired under some circumstances.